Question

If x = 3 is a root of f(x) = x^3 - 4x^3 + 7k , then find value of k​

Answer 1

Answer:

Step-by-step explanation:

f(x)=$x^{3}$-4$x^{3}$+7k

f(3)=$3^{3}$-4($3^{3}$)+7k

As 3 is a root of f(x)

f(x)=0 for x=3

∴ $3^{3}-4(3^{3})+7k=0$

9-4(9)+7k=0

7k=9(4)-9

7k=36-9

7k=27

k=27/7

Answer 2

Answer:

k=81/7

Step-by-step explanation:

1. f(x)=X^3-4x^3+7k
2. f(3)=3^3-4(3^3)+7k
3. 27-4(27)+7k
4. 27-108+7k
5. -81+7k
6. 7k=81
7. k=81/7

Hope this answer is useful to you....